Arterial Supplies of Brain and Corresponding Clinical Findings - Part 1

1. Arterial Supplies of Brain and Corresponding Clinical Findings - Part 1 13/05/03 Craig Douglas Nadine MacCowan

3. Carotid Supply • Right common carotid arises from brachiocephalic trunk • Left common carotid branches directly from the aortic arch • The ICA’s ascend through the neck, traverse the temporal bone and pass through the cavernous sinus to reach the subarachnoid space.

4. Carotid Supply • First intracranial branch is the ophthalmic artery, it travels along the the optic nerve into the orbit. Supplies retina, structures of eyeball and orbit • Also gives off post. communicating artery and ant. choroidal artery • Finally divides into ant. and middle cerebral arteries • The carotid supply provides 600-700 ml of blood every minute to the brain

5. Internal Carotid and Branches

6. Vertebral Supply • Vertebral arteries arise from subclavian vessels and course through the cervical transverse foramina. They ascend into the foramen magnum and pierce the dura, entering the cranial cavity to run alongside the medulla • They fuse at the junction of the medulla and pons to form the basilir artery • Basilir artery gives rise to cerebellar arteries and the post. cerebral arteries • Vertebral supply of 100-200 ml/min blood

7. Vertebral Supply

8. Arterial Supply of Brain

9. Anterior Cerebral Artery • Arises from ICA at almost a right angle, then runs up over genu of CC • Sends deep penetrating branches to supply the ant. portions of the basal ganglia • Supplies medial and superior frontal lobe • Supplies ant. parietal lobe

10. Anterior Cerebral Artery • Supplies: -Septal Area -Primary motor cortex (leg, foot, ub) -Motor planning areas -Primary somatosensory cortex -Most of corpus callosum

11. ACA and Branches

12. ACA and Supply

13. Basal Ganglia • Consists of caudate nucleus, putamen and globus pallidus • Initiates movement • Controls movement, by feedback to cerebral cortex • Establishes posture • Bradykinesia, dystonia and ballismus are common manifestations of disease

14. BG and Surrounding Structures

15. Basal Ganglia - Enhanced

16. Corpus Callosum • Main transverse tract of fibres connecting the two cerebral hemispheres • Primary functions are to integrate motor, sensory and cognitive performance between the hemispheres • Damage may lead to problems with sitting, standing, walking or impaired co-ordination and memory (tactile anomia)

17. Corpus Callosum

18. Septal Area • The septal area connects the hypothalamus to the mid-brain • It is believed to be involved in the integration of complex behavioural and motivational processes • Possible role in alterations of behaviour

19. Motor Cortex

22. Posterior Circulation

23. Posterior Communicating Artery • Passes posteriorly and inferiorly to the optic tract • Joins posterior cerebral artery • One of the anastomosing branches that completes the Circle of Willis • It is part of a clinically important collateral blood supply • A common site for aneurysms

24. Posterior Cerebral Artery • Curves around midbrain and passes through superior cistern • Also gives rise to several posterior choroidal arteries

25. What Does The Posterior Cerebral Artery Supply? • Medial and inferior surfaces of occipital and temporal lobes • Including hippocampus, midbrain and thalamus

26. Posterior Cerebral Artery And Strokes • About 5% of ischaemic strokes involve the posterior cerebral artery or its branches • Death is uncommon • Rate of morbidity is high

27. Symptoms and Signs Of A Posterior Cerebral Artery Stroke • Visual changes • Memory problems • Dyslexia/Alexia • Thalamic/subthalamic nuclei involvement • Cerebral peduncle involvement • Brainstem involvement

28. Visual Changes • Homonymous hemianopia – from unilateral infarction • Cortical blindness • Lack of depth perception • Failure to see objects not centred in visual field • Visual hallucinations • Disorders of colour vision

29. Memory Problems • Infarction of medial temporal lobe or medial thalamic nuclei • Usually short term memory affected • Right sided stroke: more likely to have difficulties with verbal memory • Left sided stroke: more likely to have difficulties with visual memory

30. Dyslexia/Alexia • Pure alexia may result from infarction of dominant occipital cortex • Patients may retain the ability to work out a word and its meaning if its spelt out

31. Thalamic/Subthamalic Nuclei Involvement • Infarction of the ventral posterolateral nucleus of the thalamus results in hemisensory loss – common in lacunar infarcts • Mild hemiparesis • Intention tremor

32. Hemiplegia Hemiparesis Oculomotor nerve deficit Cerebral Peduncle Involvement

33. Brainstem Involvement • Pupillary dilatation and dysfunction (especially in PCA aneurysms) • Nystagmus due to lateral medullary syndrome